Liquid detergent comprising microcapsules are very appealing to consumers. The inclusion of microcapsules in liquid detergents is desirable not only for aesthetic reasons but also for functional reasons such as isolation of incompatible ingredients, controlled and/or delayed release, etc. Ideally, the microcapsules are stably suspended in the liquid detergent and only dissolve/disintegrate in-use. This makes the design of the microcapsules technically very challenging. In-use conditions can vary widely depending on a number of factors, including cleaning temperature, hardness of the cleaning water, duration of the cleaning process, etc.
The use of microcapsules in liquid detergents is known from the literature. WO 02/055649 discloses a method for the production of microcapsules containing washing and/or cleaning substances with semi-permeable capsule shells (membranes) by means of complexing suitable polyelectrolytes.
Semi-permeable type microcapsules known from the literature do not seem to be strong enough to withstand the liquid detergent manufacture process and transport and at the same time be capable of breaking in use without leaving residues. The generation of residues is made worse under stressed use conditions, such as low temperature, hard water and short duration cleaning.
One objective of the present invention is to provide strong microcapsules for use in liquid detergents capable of dissolving/disintegrating under a wide variety of conditions including stressed conditions. In particular, the microcapsules should be suitable for use in laundry liquid detergents dissolving/disintegrating without leaving residues even when using a heavily loaded drum, a short wash cycle, low wash temperature and/or hard water.